Merge #18031: Remove GitHub Actions CI workflow.

085423b Remove GitHub Actions CI workflow. (Aaron Clauson)

Pull request description:

  While the GitHub Action CI workflow has permissions to make commits it's not suitable.

  As per #17803.

ACKs for top commit:
  fanquake:
    ACK 085423b

Tree-SHA512: 62c19dda6164a563dc87e394314afc57ef2494b7e4af148b83220f1b2b0bef9ff309b5cde5d9bed3633429b77041871993ac5c73b0cbe7f720d6a4e60e3e816a

Author: fanquake